1. Field of the Invention
This invention relates to an improved contactor control system, and more particularly, it relates to several modular units for a contactor control system which easily interconnect both electrically and mechanically to a main contactor module and to each other.
2. Description of the Prior Art
Generally, a contactor control system controls the energization of a load for a power source, such as a three phase motor with several horsepower ranges which may go as high as 600 volts. This contactor control system is comprised of several components, such as a contactor, a starter protector or an overload unit, a controller, a communication unit, a display unit, and a push button unit.
As is well known in the art, a contactor contains a relay to open or close a circuit. A starter protector, commonly known as an overload unit, provides protection for an overload current as well as phase loss and/or unbalance. A controller turns the contactor on and off. A communication unit communicates with the controller. The display unit provides a visual indication of the status of the controller, and the push button station allows human interface to the controller.
A contactor with a motor controller is an electromagnetic coil which acts as a switch for connecting a motor to a device for operating the device. Generally, a conventional type of contactor with a motor controller may have one or more of the following features: a means for protecting the motor from overheating and from phase and/or current unbalance or loss, a trip setting adjustment, a test function, a bell alarm function, which is a NO/NC relay indicating the state of the trip or that there is an overload, and a reset function which provides a reset from the tripped status.
Recently, a more advanced contactor control system with a motor controller has been developed having the capability of incorporating one of more of the several features of the conventional type of contactor with a motor controller discussed in the preceding paragraph and, additionally, has the capability of incorporating a communication system which consists of a computer and adding one or more external control options. These external control options, while being an improvement over the conventional type of contactor with a motor controller discussed in the preceding paragraph, are generally poorly organized, increase the size of the contactor control system, overlap in their functions and the services they provide, and require an extensive cabling system which generally extends over the hinges of the door providing access to the housing of the contactor control system.
In some of the present-day contactor control systems, the overload module may be connected mechanically to the contactor through a snap connection means, but no electrical connection is made therebetween, thereby requiring several cable lines and wiring. All of these contactor control systems generally place the protection units closest to the overload module, followed by the control modules, and followed by the communication and display modules. Some disadvantages of this organization for the several modules for a contactor control system are the increased assembly costs and the increase in the wire and cable connections. These present-day contactor control systems also require that each component be individually mounted to a mounting panel or on a rail and interconnected electrically through a network of cables and/or wires which are also carried by the mounting panel or rail. This system requires a great amount of space and time in the assembling of these several components onto the mounting panel or rail.
There remains, therefore, a very real and substantial need in the art to provide an improved contactor control system which eliminates one or more of the several disadvantages associated with the conventional type of contactor control system.